There is appreciable interest in production of food products having two, three, four or more ingredients; the food product usually includes a bottom food patty of a food material (e.g., chicken, turkey, pork, or veal) covered by a top food patty of the same or a different material. One or more additional ingredients, most often somewhat smaller than the top and bottom patties, are usually interposed between those patties. Typical products of this kind utilize chicken or turkey meat for the outer patties, with cheese, ham, stuffing, or condiments for the middle layer ingredients. A variety of other similar products are possible, including fish with crab or other stuffing as the middle ingredient, and beef or other meat with a variety of ingredients in the center of the food product. In any of these products, the top and bottom patties should be sealed together to afford a coherent plural-layer food product.
There are a number of high efficiency, high volume food patty molding machines that have been utilized for production of hamburger patties, other ground meat patties, chicken patties, fish patties, imitation steaks, and other molded food products. Four such machines that are commercially available are described in Richards et al. U.S. Pat. No. Re. 30,096, Sandberg et al. U.S. Pat. No. 4,054,967, LaMartino et al. U.S. Pat. No. 4,182,003 and Sandberg U.S. Pat. No. 4,768,260; these machines are available as the F26, F-19, F-12 and F-6 food patty molding machines, respectively, made and sold by Formax Inc. of Mokena, Ill., U S.A.
All of these high volume food patty molding machines are relatively flexible and each can produce a wide variety of food patties, depending upon the mold plate configuration and other mold station components in the machine. All can be used to produce molded food patties of whole muscle fiber, using the molding apparatus of Sandberg et al. U.S. Pat. No. 4,356,595 or Sandberg U.S. Pat. No. 4,697,308. However, these machines do not directly manufacture food products having two or more ingredients; additional equipment is required. This applies also to other food patty molding machines, particularly those that, like the machines identified above, use a reciprocating mold plate.
One known system for producing plural-layer food products uses two of the Formax F-19 patty molding machines of Sandberg U.S. Pat. No. 4,054,967, with one of those machines modified for a pass-through operation. That system deposits cheese, ham, condiments, or other ingredients onto a series of bottom food patties to form multi-layer food subassemblies on a continuously moving belt conveyor. A second, modified patty machine is used to deposit a top patty on each multi-layer subassembly to complete a food assembly, followed by a mechanism for "knitting" each assembly together to complete the food product. The system and its components are disclosed in a series of United States Patents of Oscar Mayer Foods Corporation; those U.S. patents are Jonovic et al. No. 4,684,040, Borsuk No. 4,709,449, Hartl et al. No. 4,714,014, and Mally et al. No. 4,716,821 and No. 4,832,970.
Maintaining registry between sequential plural layers of a food assembly, on a continuously moving conveyor, is quite difficult. The least variation in timing sequence for any part of the system is likely to produce an unacceptable end food product due to misalignment of layers of that product. A "knitting" mechanism that relies on multiple piercing operations to join two superimposed food patties, as in the previously discussed system, is likely to be unreliable whenever misalignment occurs; it is also difficult to attain reliable, consistent operation of equipment of this kind when working on the fly, with a continuously moving conveyor. Further, it may be noted that equipment on the Oscar Meyer line is all driven mechanically through a common drive shaft that limits flexibility of changes, additions, or deletions of equipment. Electronic sequencing is much preferable.